Down a pool if a monitor fails?

Wow....That's awesome.

Hoolio's idea is interesting.

I would suggest doing it in two parts.

Part 1: Custom Health Monitor...

Type: HTTP

Send String: GET /monitor/status.html

Receive String: SUMMARY: OK

Part 2: iRule for Redirect when no pool members are available, redirect to a pool or another website.

when HTTP_REQUEST {
   Check if the default pool has less than one active member
  if { [active_members [LB::server pool]] < 1 } {
    HTTP::redirect "http://www.google.com"
    pool alternate.pool.of.servers
  }
}

http://devcentral.f5.com/Wiki/default.aspx/iRules/LB__server.html

The Server Administrators would then have to take down all of the servers themselves, and then the F5 iRule would redirect the Traffic. It would make it harder for one of them to "accidently" take down the entire pool and causing an outage, and would allow them to take down individual servers for troubleshooting.

Just a thought.